An earth tremor struck parts of southeast England Saturday morning, residents said. Some witnesses said cracks appeared in walls, and chimneys collapsed across parts of Kent county. Kent Police said they believed there had been an earthquake and emergency services were responding. Residents said a tremor lasting about 10-15 seconds struck at around 8:15 a.m. (0715 GMT). The tremor measured at 4.7 on the Richter scale.